Geared limit switch



June 29 1926. 1,590,471

W. E. MENZIES GEARED LIII IT swrrca Filed Sept. 23, 1921 2 Sheets-Sheet 2 WITNESSES: INVENTOR MZ/um Nenz/as QR. BY

XQ A

Patented June 29, 1926.

UNITED STATES WILLIAM E. MENZIES, OF

IRWIN, PENNSYLVANIA, ASSIGNOR TO WESTINGHOUSE ELECTRIC & MANUFACTURING COMIPANY, A CORPORATION OF IPENNSYLVANIA.

GEARED LIMIT SVVITCII.

Application filed September 23, 1921.

My invention relates to geared limit switches and it has particular relation to such devices as may be employed in connection with internal-combustion engines for isolated electric plants or the lil;

My invention has for one of its objects to provide a limit switch that may be easily and conveniently adjusted for operation at a desired future time.

A second object of my invention is to provide a limit switch having means for indicating the period of time that must elapse before the switch is effective.

A further object of my invention is to provide a gear mechanism for limit switches having a relatively high ratio between the driving and the driven members and which occupies comparatively little space.

The details of my invention will be described in connection with the accompanying drawings, in which Figure 1 is a top view of a limit switch constructed in accordance with my invention, a portion of a driving shaft and certain stationary supporting means being shown therewith.

Fig. 2 is an end view of the limit switch as viewed from the left in Fig. 1.

Fig. 3 is a view, in transverse section,taken on line IIIIII of Fig. 1.

Fig. 4 is a view, in axial section, taken on line IV IV of Fig. 2.

Fig. 5 is a view of the stationary contact member of the limit switch together with a portion of its associated parts.

Fig. 6 is a diagrammatic view of circuits and apparatus of an ignition system of an internal-combustion engine with my improved limit switch applied thereto.

Referring to the drawings, a limit switch 1 comprises a stationary casing member 2, a rotatable easing member 3 that contains a reduction gear mechanism 4, a casing memher 5, which may be adjustably secured to the stationary member 2, a driving shaft 6 that may be connected to any suitable rotating part of an engine or similar device, a movable contact member 7 that is connected to the rotatable casing member 3 and a coactirig stationary contact member 8 that is mounted on the stationary casing member 2. The stationary easing member pro p .1; a j .lphcml flange in has ".iitnble screw or h ll. holes 1! to! Serial No. 502,605.

the member 2 to any suitable stationary portion of a gas engine or similar device. The casing member 2 is, also, provided with a centrally-disposed sleeve-like projection 12 and with a circumferential opening 13 that is covered by transparent material such, for example, as glass 14;. The stationary contact member 8, which may be of any suitable size and form, is here shown as rectangular in cross-section. It is mounted upon, and insulated from, the stationary casing member 2 and is electrically connected to the i iition system, as will be explained in connection with Fig. 6.

The casing member 5, which is operatively connected to one member of the reduction gear mechanism tit, is provided with a centrally-disposed sleeve like projection 15 to be received by the sleeve-like projection 12 of the casing member 2. The member 5 is provided, also, with a screw-threaded projecti on 16 upon which mounted a thumb-nut 17, whereby the members 2 and 5 may be rigidly clamped together for the purpose of preventing relative movement. A thumbnut 18 provides a convenient means for adjusting the position of the plate member 5 and its connected parts relatively to the casing member 2 when the thumb-nut 17 has been loosened to permit such adjustment.

The rotatable casing member 3 is provided with an annular plate 19 which sur rounds the projection 15 of plate member 5 and permits relative rotative movement of the casing member 3 and the member 5. The latter members maintain the various parts of the reduction-gear mechanism 4 in operative relation, as will be hereinafter set forth. The member 3 is provided with a central projection 20 to provide a bearing for the driving shaft 6. The casing member 8 is provided, on its periphery, with a dial 21 that is calibrated, for example, to indicate the number of hours of operation of the shaft 6 at a given rate to effect the engagement of the contact members 7 and 8 of the limit switch from any relative position to which they have been adjusted or actuated. The dial may be read through the transparentmember 14.

Referring particularly to Figs. 3 and 4, the reduction-gear mechanism comprises duplicate units or seri of piniona and ear when, nly one of which will, be desert ed.

is grounded.

in detail. The shaft 6 is provided with a small pinion 22, which may be termed a sun pinion, that meshes with a floatingring gear wheel 28 that may be termed a planet gear. The gear wheel 23, in turn, meshes with a pair of internal gear wheels 24 and each of which is one-half the thickness of the gear wheel 23 and the pinion 22. The gear wheels 2% and 25, which are respectively secured to, and loosely mounted within, the casing member 3, are respectively provided, for exatnple, with seventy-two and seventy=three gear teeth. A disk 26, which maintains the relative axial position of the several gea wheels, is connected to the gear wheel 25 for rotation therewith.

"With the gear wheels arranged as described above, one revolution of the ring gear wheel about the central axis of the system, advances the gear wheel 25 relatively to the gear wieel 24;, a distance equiv- 'a-lent to the width 01" one tooth of the gear wheel 25. Accordingly, seventy-three revolutions of the gear wheel 23 are required to rotate thegear wheel 25 through 360. It, for example, eight revolutions of the pinion 22 are required to eti ect one revolution of the gear wheel live hundred eightyfour revolutions of the pinion 22 are required to sheet a complete revolution of the wheel inasmuch as the disk 26 is connected to a sun pinion 27 of an arrangement comprising gear wheels 28, 29 and 80 corresponding, respectively, to gear wheels 23, 2a and 25, it will be evident'that the number of revolutions of the shaft 6 required to etl'ect a complete revolution of the last member of the train of mechanism is 2 or, approximately, a ratlo of 342,000

to-l.

Thesecond portion ot'the'tram of gear mechanism is located between the dlsk 26 and the plate member 5, the latter belng connected to the internal gear wheel 30 which is the last member of the tram and whlch -'re1n-ains stationary when the member 5 is singlecylinder internal-combustion engine.

Energy is supplied from the ungrounded side of a battery 32 through a manually operable switch 33, an interrupter 34 and the primary winding 35 of an induction coil 86 to ground. The secondary winding 37 of the induction coil isconnected in circuit with sparkplug 38, one terminal of which hen the manually-operable switch 33 is closed, the ignition circuit is operative. lhe'limit switch 1 is connected in shunt-circuit relation to the interrupter.

Vfh'en the contact members 7 and 8 are not in engagement, as illustrated in Fig. 6, the

desired.

limit switch does not atlect the operation of the system. When, however, the switch has operated to etl'ect engagement of contact members '7 and S, the interrupter 134i is shortcircuited and the engine is brought to rest because the interrupter is ineffective to make or break the circuit for the production of spar-heat the spark plug 38.

In the operation of the limit switch, the shattb, which may be operatively connected to the cam shaft 40 of an internal-combustion engine, isdriven at a substantially constant speed. If it is desired to operate the engine for driving an electric generator to charge a storage battery, the length of time required to charge the battery may be obtained in any desired or well known manner. For example, the specific gravity of the'battery is measured by a hydrometer and the number of hours required to charge the battery may be computed therefrom or secured from a table, or the hydrometer nay be calibrated to read directly-the number of hours requlred to fully charge the battery. The limit switch isthenadjusted to an initial position by loosening the thumb-nut 17 and rotating the plate member 5, together with the casing melnber 3 and the reduction-gear mechanism contained therein, until the numher on the dial corresponds to the number of hours computed or indicated as necessary to charge the battery. lhe thumb-nut 17 is then tightened to maintain the relative po sitions of the plate member 5 and the stationary member 2.

Since the gear wheel is stationary, the rotation of shaft 6 and the p1n1on22 effects rotation of the several members of the train,

relatively to gear wheel 30, to effect the rotatron of the casing member 3, the dial thereon and the movable contact member 7 carried thereby. The dial indicates, at any given time, the number of hours required to complete the charging operation. Then the dial indicates zero, the contact members 7 and 8 are in engagementand the engine is brought to rest.

It is to be understood that the limitswitch mayoperate to open the ignition circuit instead ofmerely short-circuiting a portion thereof, shown and desc-ribed'herein. It will-be "understood, further, that the dial of the limit switch may be calibrated in any suitable units such, for err-ample, as the specific gravi-ties of th'e'battery which correspond to periods-of time necessary for charging the battery. l[--ma-y, also, arrange clamp the movable casing member and the dial and the movable contact anember on the adj'ustable port-ion of the casing". The number of gear units may be -increased it These and other modifications will be apparent to those skilled in the art to which my invention appertains.

It will be noted that'I have vgroi'ri'de'd"an arrangement whereby the operation of a limit switch may be predetermined within definite limits by extremely simple and efficient means. A limit switch constructed in accordance with my invention provides an exceedingly high gear reduction by means of mechanism consisting of comparatively few parts and the members of which are of sufficient size to provide gear teeth of ample cross-section to provide the necessary mechanical strength. The entire device may be mounted in a very small space at a posi tion that is convenient for observation and manual adjustment.

I claim as my invention:

1. The combination with a stationary member and a casing having relatively movable parts one of which is adjustably secured to said stationary member, of coacting contact members respectively carried by said stationary member and one of said casing parts, a reduction gear mechanism within said casing for operatively connecting said casing parts, means for actuating said gear mechanism, and means carried by one of said casing parts for indicating the time required to effect the engagement of said contact members from any relative position of the latter.

2. The combination with a rotatable member, a reduction gear mechanism, and a casing therefor secured to a member of said mechanism, of coacting contact members respectively connected to said casing and to a relatively movable member of said mecha nism, and means for adjustably securing another member of said mechanism whereby actuation of said rotatable member eflects rotation of said casing and relative movement of said contact members.

3. The combination with a reduction gear mechanism, and a casing therefor having a plurality of parts respectively connected to members of said mechanism, of coacting contact members carried by certain of said parts and adjustable means for restraining rotation of one of said casing parts Whereby relative movement between said contact members is produced.

4. The combination with a member having an opening, a second member projecting through said opening and adjustable means for preventing relative movement of said members, of a third member rotatably mounted on the second member, coacting contact members carried by said second and said third members, and a reduction gear mechanism for operatively connecting said second member and said third member.

5. The combination with a member hav ing an opening, a second member projecting through said opening and adjustable means for preventing relative movement of said members, of a third member rotatably mounted on the second member, coacting contact members carried respectively by said second and said third members, a reduction gear mechanism supported by said third member and operatively connected to the latter member and to said second member, and an actuating member for said mechanism.

In testimony whereof, I have hereunto subscribed my name this 6th day of September 1921.

WILLIAM E. MENZIES. 

